Tangential flow pulse jet pump propulsion for water craft

ABSTRACT

Propulsion mechanism for water craft comprises a power driven pulse jet pump which operates at a selected shallow immersion depth, preferably on a smooth wake created by a planing surface of the craft. The pump comprises a propulsion wheel having concavo-convex curved blades mounted with their concave sides facing in the direction of forward rotation of the wheel, and the tip edges of the blades are sharpened. At and above cruising speed the blades are immersed substantially less than one half of their width, and are so angularly adjusted that each blade slices cleanly into the wake and in effect severs a &#39;&#39;&#39;&#39;chip&#39;&#39;&#39;&#39; of water therefrom in somewhat the same manner as a blade of a power wood planer or metal-milling cutter. These water &#39;&#39;&#39;&#39;chips&#39;&#39;&#39;&#39;, by inertia, are forced upwardly and around the concave faces of the blades, so that by a combination of the rotative orbit of the blades, and their curved conformation, the &#39;&#39;&#39;&#39;chips&#39;&#39;&#39;&#39; are discharged rearwardly through the air at a velocity greater than the tip speed of the blades, thereby generating a reaction thrust which propels the craft forward. The wheel preferably is vented to act additionally as an air impeller so as to discharge a high velocity air stream rearwardly along with the pulse jet stream of water &#39;&#39;&#39;&#39;chips.

Uited States Patent [1 1 Quady Sept. 18, 1973 TANGENTIAL FLOW PULSE JET PUMP PROPULSION FOR WATER CRAFT Primary Examiner-Milton Buchler Assistant Examiner-Donald W. Underwood AttorneyGeorge E. Pearson [57] ABSTRACT Propulsion mechanism for water craft comprises a power driven pulse jet pump which operates at a selected shallow immersion depth, preferably on a smooth wake created by a planing surface of the craft. The pump comprises a propulsion wheel having concavo-convex curved blades mounted with their concave sides facing in the direction of forward rotation of the wheel, and the tip edges of the blades are sharpened. At and above cruising speed the blades are immersed substantially less than one half of their width, and are so angularly adjusted that each blade slices cleanly into the wake and in effect severs a chip of water therefrom in somewhat the same manner as a blade of a power wood planer or metal-milling cutter. These water chips, by inertia, are forced upwardly and around the concave faces of the blades, so that by a combination of the rotative orbit of the blades, and their curved conformation, the chips are discharged rearwardly through the air at a velocity greater than the tip speed of the blades, thereby generating a reaction thrust which propels the craft forward. The wheel preferably is vented to act additionally as an air impeller so as to discharge a high velocity air stream rearwardly along with the pulse jet stream of water chips.

19 Claims, 10 Drawing Figures PATENIEDSEPIBW 3.759.213

SHEEI 1 BF 5 I BY "6% I AT iORNEY Pmsmmsm 3.759.213

25 FIG. 4

INVENTOR. L.- JOHN C.QUADY FIG 2 BY ATTORNEY PATENTED 8!? I 81975 3. 759 .2 l 3' saw u [If 5 JOHN C. QUAD? ATTORNEY TANGENTIAL FLOW PULSE JET PUMP PROPULSION FOR WATER CRAFT BACKGROUND OF THE INVENTION Various types of wheels have previously been employed to propel water craft, and some of these wheels have been provided with curved blades. A study on such wheels is reported on in a publication of Naval Ship Research and Development Center dated Sept. 1969, No. ATD-l 1. So far as is known, however, such prior type propulsion wheels lack an important feature of the present invention, and such loose water as is caused by the normal and designed operation thereof is incapable of attaining a discharge speed in excess of the tip velocity of the wheel.

PURPOSE OF THE INVENTION A primary object of the present invention is to propel a water craft by means of a pulse jet pump having a wheel with concave-convex curved blades mounted with their concave sides when at the bottom of the wheel facing aft. The pump is mounted so that at cruising speed and above, preferably the wheel operates on a smooth wake created by forward motion of the boat in the water. The immersion depth and speed of rotation, of the wheel, and the tip entrance angle, width and curvature of the wheel blades are so designed, that each successive blade severs and elevatesa segment or chip" of water from the surface of such wake and discharges it rearwardly at high speed, preferably along an air stream generated by the rotation of the wheel. The blades optionally are rotatively adjustable about individual axes parallel to the axis of wheel rotation, in which case blade adjusting means may be provided to adjust all of the blades simultaneously.

The foregoing objectives and advantages of the invention will be apparent from the following description and the accompanying drawings, wherein:

FIG. 1 is a fragmentary, somewhat diagrammatic, side, elevational view of the stern portion of a boat having propulsion means incorporating the present invention mounted therein, portions of the internal mechanism being shown in broken lines.

FIG. 2 is a top plan view of FIG. 1.

FIG. 3 is a fragmentary, diagrammatic, sectional view through one of the drive wheels of FIGS. 1 and 2 taken along a fore-and-aft vertical plane, the action of the lower blades on the flat wake being shown, other blades being omitted.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a fragmentary sectional view of the lower portion of a wheel generally similar to that shown in FIG. 3 but having angularly adjustable blades.

FIG. 6 is a fragmentary sectional view taken along line 6-6 of FIG. 5.

FIG. 7 is a side elevational view of a modified form of drive wheel embodying the invention with gear driven blade adjusting and reversing means.

FIG. 8 is an elevational view looking in the direction of the arrows 8-8 of FIG. 7, portions being broken away.

FIG. 9 is a diagram showing successive stages in the action of a blade during the severing, elevating and discharging of a water chip element of the pulse jet stream for propelling a vessel upon which the blade is mounted.

FIG. 10 is a diagram in the nature of a perspective view showing in perspective successive stages the severance and discharge of a water chip" from the flat wake.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings in detail, and considering first the non-adjustable vane structure of the pulse jet pump embodying the invention shown in FIGS. 1 4, a pair of propulsion wheels A and B are mounted on power driven shaft means 10 journaled to extend transversely ofa hull C. The type of hull, the number and location of drive wheels, and the type and arrangement of power drive mechanism employed are not, per se, features of the invention, and are subject to usual selection and modification by the designer of a craft in which the invention is to be embodied. Details thereof are, therefore, omitted.

The illustrative hull C is of planing type, and the propulsion wheels A and B are mounted in housing recesses 11 and 12, respectively, provided one in each side of the hull near the stern. Since the wheels A and B are similar, only the port one B is illustrated and described in detail herein.

The illustrative hull C has a conventional forward step 13, and the hull bottom 14 ahead of the drive wheel B preferably is flat, so as to create a flat wake 15, see FIGS. 1, 3, 9 and 10, upon which the wheel B operates. Optionally a step vane 17, see FIGS. 1 and 2, may be mounted in a shallow recess provided in the hull bottom ahead of the wheel, and is adjusted by a conventional jack 19 about a forward, transverse pivotal axis 20, thereby to control the level of the flat wake and the immersion depth of the wheel.

The wheel B comprises a pair of side disks 21 and 22 fixedly secured co-axially on the shaft means 10, the latter being journaled in usual water tight bearings 23 and 24, see FIG. 4, in the hull C. A pair of conventional internal combustion gas turbines D and E are arranged to drive the wheels A and B through suitable transmission mechanism F. While a well known type of rightangle drive transmission mechanism F is illustrated, it will be understood that the engine or engines may be mounted axially parallel to the propulsion wheels, in which case suitable alternate type transmission mechanism of a well known type will be employed.

A plurality of concavo-convex blades 25 of suitable material, such as, for example, stainless steel, extend between the disks 2] and 22 with the concave sides of the blades facing in the direction of forward rotation of the drive wheel B. While the blades illustrated herein are shown as of substantially right circular cylindrical curvature, the specific curvature is not a feature of the invention, and tests and calculations at this stage of development are not conclusive as to an optimum size or shape for the blades.

The plane defined by the longitudinal edges of each blade 25, and represented by broken line 27 in FIG. 3, is tilted rearwardly toward the blade tip by an angle 28 relative to a radial plane of the wheel, represented by broken line 29, through the blade tip 30. The magnitude of this angle 28 is such that the designed ratio of the wheel peripheral speed to the relative speed of the flat wake 15 provides a positive angle of attack of the blade tip, which causes the blade during each orbit to scoop a chip" of water from the flat wake. The radial width and curvature of the blade and the position of its exit portion are such as to cause the chip to leave the blade at a speed greater than blade tip speed in an essentially horizontal rearward direction. The tip of each blade preferably terminates in a sharp, cutting edge so as not to disturb the smooth flow of water onto and around the curved concave face of the blade, as shown in successive stages in FIGS. 3, 9 and 10.

In order to take advantage of the similarity of the propulsion wheel to an ordinary axial inflow, tangential discharge, squirrel cage blower, and thereby to derive some thrust from what otherwise might be wasted energy in dragging air around with the wheel, air inlet holes 31 are provided in the wheel disks 21 and 22, see FIGS. 3 and 4, to admit ambient air from the wheel recesses 11 and 12 into the space between the disks. Such air is discharged rearwardly from the wheel.

Referring to FIGS, 3, 9 and 10, the wheel operates at a height relative to the flat wake 15 which causes each blade 25, as it approaches and passes the nadir of its orbit, to sever a chip" 33 of water from the surface of the wake. Each chip so severed from the wake water by the rapid, rearward and downward orbital movement of the blade 25, by inertia flows upwardly and then rearwardly around the concave face of the severing blade, and is discharged thence rearwardly at a velocity substantially greater than blade tip speed. Upward movement of the blade as it approaches the discharge position assists in clearing the chip from the blade.

As at present visualized the relative movement of a blade, and the flow path of a water chip 33 severed thereby is shown diagrammatically in FIG. 9 in successive stages, numbered 33b to 33s.

The blade is shown at 2511 in FIG. 9 at the instant it contacts the wake 15, the next following blade being also shown only at this same instant. The upper horizontal dash-dot line 35 shows the path of movement of the wheel axis, along which it moves at hull velocity, V, the point Ca showing the location of the axis when the blade is at 25a, the tip radius at this stage being shown at Ra.

At 33b the chip" is partially severed from the wake, and has started its upward flow movement around the concave face of the blade which at this stage is shown as 25b.

At 330 the direction of flow of the upper portion of the chip relative the blade has been reversed, the lower portion of the chip" still flowing upwardly along the concave face of the blade 250.

At 3311 the flow direction of the entire chip relative the orbital movement Vp of blade 25c has now been reversed, and as the chip nears the upper edge of the blade, upward orbital movement of the blade assists in clearing the chip" from the blade 25d.

At 33e the chip is cleared from the blade 25a and is moving rearwardly through the air at a speed in excess of the orbital velocity Vp of the blade.

In order to provide a quantitative explanation of the operation of the tangential flow pulse jet propulsion pump of this invention, a simplified derivation of the approximate mass flow, exit velocity, thrust, and efficiency of the invention is best shown in FIGS. 9 and 10, and is calculated as follows:

Referring to these FIGS. 9 and 10, and more particularly to FIG. 10, assume that the radius R of the propulsion wheel is large compared to the radial projection, a, of the blade aperture, and that the linear speed of a blade at the nadir of its orbit relative to the wake is substantially greater than the speed V of the craft relative to the wake. In the following equations: Vp Average linear speed of the blade. V Velocity of the craft velocity of the flat wake relative to the wheel axis. d the average depth of cut of the blades into the wake. w the width of cut of the blades. p the mass density of the water. Then, the average mass of fluid entering the wheel per unit time is given by:

Also, in order to develop thrust, Vp must be greater than V. Then the average inlet velocity of the fluid, Vi relative to the blade as it picks up a chip of water is given by:

Eq. 2. Vi= Vp- V Due to the low value of the kinematic viscosity of water, the effect of fluid friction in slowing down the velocity of the fluid relative to the blade is expected to be small. Hence, for this simplified analysis, friction will be neglected and the velocity of the fluid relative to the blade as it leaves the blade is still equal to the inlet velocity.

But the blade itself has an average velocity Vb relative to the still water of the wake of:

Eq. 3. Vb=Vp V Hence, the average exit velocity, Ve of each chip relative to a reference point stationary in the water is given by the sum of Vi and Vb, i.e.

Eq. 4. Ve= Vi+Vb=(Vp- V)+(Vp V) 2 (Vp V) The average thrust, T, exerted by the wheel on the water is equal to the average rate of change of momentum of the mass of water acted on by the wheel. Thus, thrust is the product of the average mass flow of fluid, (dM/dt), and the average change in velocity of the fluid, Ve as it is acted on by the wheel, i.e.

The useful work done per unit time by the wheel in propelling the craft at velocity V, is the power output, P0 which is equal to the product of average thrust and velocity.

Eq. 6. P0 T V The input energy exerted on the water per unit time Pi is equal to the product of average thrust and peripheral speed of the blades. Thus Eq. 7. Pi=T' Vp The propulsive efficiency of a screw propeller or other propelling device is the ratio of the useful power out to the input shaft power applied. Thus, neglecting friction, gravity and other minor effects, the efficiency, E, of this propulsive device is given simply by:

Eq. 8. E (Po/Pi) (T V/T' P) P) OPERATION In the form of the invention shown in FIGS. 1 4,

when the hull C is at rest, or moving at slow speed, either forward or in reverse, the wheels A and B will be at their normal displacement depth, indicated by broken line 34 in FIG. 1, will create no flat wake, and will be lower in the water than when the hull is moving at a forward speed sufficient to create the flat wake 15. The wheels A and B will at such times act like prior art paddle wheels, moving water without elevating it in the direction of movement of the lower portion of the wheels to propel the hull in the opposite direction. Care should be exercised in this mode of operation to avoid high rotative speed of the wheels which would cause undue cavitation and reduction of propulsive effect.

By gradually increasing the forward speed of the wheels A and B, the hull C comes up onto a plane, and the illustrated flat wake is created, the step vane 17 being adjusted as required, to provide an optimum immersion depth for the wheel blades for cruising and high speed operation as described previously herein.

MODIFICATION OF FIGS, 5 AND 6 In the modified form of the invention shown in FIGS. 5 and 6 provision is made for changing the forward operating angle of all of the blades simultaneously, the propulsion wheel being otherwise generally similar to the wheels shown in FIGS. 1 4, and described in detail previously herein. Since most parts of the propulsion wheel of FIGS. 5 and 6 are generally similar to their counterparts shown in FIGS. 3 and 4, corresponding parts of the embodiment shown in FIGS. 5 and 6 are designated by the same reference numerals as in FIGS. 3 and 4 with the prime added.

The drive wheel B of FIGS. 5 and 6 comprises a pair of axially outer disks 40 and 41, and a pair of axially inner disks 42 and 43, of smaller diameter. The outer disks 40 and 41 are fixedly secured coaxially to drive shaft means 10, and the inner disks 42 and 43 are secured to a hub 45, journaled on the shaft means 10', and with each inner disk adjacent an outer disk. Each of the blades 25 is pivotally connected adjacent its tip, by a pivot pin 47, to the rotatively driven outer disks 40 and 41, and is notched out to clear the inner disks as shown in FIG. 6. An actuator pin 48 is secured to the radially inward portion of each blade 25' and projects laterally into radially extending slotted holes 49 and 50 provided, respectively, in the inner disks. As the inner disks are rotatively adjusted between their solid line and broken line positions of FIG. 5, the blades 25 are swung between their solid and broken line positions, respectively, of said figure. Since numerous suitable actuating means for relatively adjusting the inner and outer disks will be obvious to any ordinarily skilled designer or engineer, and since such actuating means are not, per se, a feature of the present invention, such means are omitted.

Registering air inlet holes 31 are provided in the outer and inner disks, on each side of the wheel B, the holes in the inner disks being elongated circumferentially of the disk sufficiently to avoid obstructing the holes in the outer disk in any relatively adjusted position of the blades 25'.

Other than for the adjustability of the blades, the operation of the wheel B of FIGS. 5 and 6 is similar to that described previously herein for the wheel B of FIGS. 1 4.

MODIFICATION OF FIGS. 7 AND s In a further modified form of the invention shown in FIGS. 7 and 8 a propulsion wheel G comprises a plurality of similar spider wheels 52, secured co-axially, and in axially spaced relation, on a hub 53. The latter in turn is secured co-axially and co-extensively on an end of a power driven hollow shaft 54. A stub shaft 55 is secured to extend co-axially from the other end of the hub 53, the shafts being journaled in usual ball bearings, not shown.

A plurality of hemi-cylindrical, bucket-like blades 57 are mounted for pivotal adjustment between each adjacent pair of the spider wheels 52, the blades 57 between the successive pairs of spider wheels being arranged in symmetrically arranged rows, and the blades of each row fixedly connected to rotate co-axially in the spider wheels. A pair of blade-adjusting gear segments 58 and 59 are fixedly mounted one on each end of each row of the blades 57 exteriorly of the outermost spider wheels 52. A pair of blade-adjusting gears 60 and 61 are pivotally mounted, one co-axially exteriorly of each outermost spider wheel, each of said gears being in mesh with all of the blade adjusting gear segments on the same end of the assembly as the gear.

A blade adjusting hydraulic cylinder 62 is linked between each outermost spider wheel and the bladeadjusting gear adjacent thereto. Selective extension and retraction of these hydraulic cylinders rotatively adjusts the blade-adjusting gears 60 and 61, and thereby the blades 57, relative to the wheel 52.

A cylindrical hydraulic reservoir 63 is provided coaxially in the hub 53, and high pressure tubes 64 and 65 communicate the ends of this reservoir with opposite ends of each hydraulic cylinder 62. A hydraulic piston 67, with usual O-ring seals 68 is mounted in the reservoir 63, and is actuated by a thrust rod sealed at 69 and mounted for axial movement in a bore provided therefore co-axially of the drive shaft 54.

The angular adjustment provided by the structure shown in FIGS. 7 and 8 not only provides means for adjusting the angle of the blades for optimum performance of the blades for cruising and high speed performance, but also for more effective performance in reverse.

The invention provides a simple, effective, high speed, low draft, propulsion mechanism for water craft wherein a minimum of wetted surface, and therefore surface drag is encountered, and which has capability for extremely high speed and efficient operation.

Having thus described my invention, what I claim as new and useful and desire to secure by U. S. Letters Patent is:

1. Pulse jet pump type propulsion mechanism for a water craft comprising, in combination with a hull,

a planning surface on the hull for providing a smooth wake astern thereof with the craft moving ahead at and above a selected speed,

a propulsion wheel journaled on the hull for rotation about an axis extending transversely of the hull above the zone of such wake,

a plurality of concavo-convex curved blades mounted peripherally about said wheel, each blade having its concavely curved face of selected width and curvature for facing in the direction of forward rotation of the wheel, the wheel being mounted at a height on the hull to immerse only a selected tip portion of each blade in such wake at the nadir of blade orbit with the craft traveling forward at and above such selected speed, and

power drive means for rotatively driving the wheel in its forward direction at a peripheral speed sufficiently greater than such selected hull speed that the tip of each blade severs such chip-like segment of water from the surface of such wake, and propels such segment by inertia radially inwardly around the concave face of the blade, the curvature of each blade at its radially inward edge continuing past a radial plane of the wheel tangent thereto, whereby each such segment is discharged rearwardly above such wake at a speed greater than blade orbital speed.

2. Propulsion mechanism as claimed in claim 1 wherein the tip of each blade is so angularly positioned relative to a radial plane from the wheel axis through the blade tip that with the hull traveling forward at a speed to create such wake, and the wheel rotatively driven to sever and propel such chip-like segments from the wake, the blade tip enters the wake at a relative angle of attack to cut smoothly into the wake.

3. Propulsion mechanism as claimed in claim 2 wherein the relative angle of attack of the blade is slightly positive.

4. Propulsion mechanism as claimed in claim 1 wherein the tip of each blade is sharpened to a cutting edge.

5. Propulsion mechanism as claimed in claim 1 wherein a wake-creating element of the hull bottom ahead of the wheel is adjustable for controlling the immersion depth of the wheel in the wake, and means for adjusting said wake creating element.

6. Propulsion mechanism as claimed in claim 1 wherein each of the blades is angularly adjustable relative to a radial plane from the axis of wheel rotation to a selected portion of the blade.

7. Propulsion mechanism as claimed in claim 6 wherein all of the blades are operatively interconnected for synchronous angular adjustment.

8. Propulsion mechanism as claimed in claim 7 wherein each of the blades is rotatively adjustable about an axis parallel to the axis of wheel rotation, and all of the axes of blade adjustment are spaced equally from the axis of wheel rotation.

9. Propulsion mechanism as claimed in claim 8 wherein the blades are adjustable from a position wherein their concave sides face in the direction of forward rotation of the wheel, to a position wherein their concave sides face in the direction of reverse rotation of the wheel.

10. Propulsion mechanism as claimed in claim 9 wherein a gear segment is secured to each blade coaxially of its axis of adjustment, gear means mounted co-axially of the wheel and in mesh with a gear segment connected to each blade, said gear means being rotatively adjustable about the axis of wheel rotation, and actuating means operatively mounted between the gear means and the wheel to control the rotative position of the gear means relative to the wheel, and thereby the adjusted angular position of the blades.

11. Propulsion mechanism as claimed in claim 10 wherein the wheel comprises a hub having a cylindrical hydraulic compartment co-axially therein, a plurality of spider wheels mounted co-axially on the hub in symmetrical, axially spaced relation, a plurality of blades mounted in aligned rows between the spider wheels, the blades of each row being interconnected to each other and to at least one of the gear segments for rotative adjustment about a common axis parallel to the hub axis, the actuating means comprises a hydraulic actuator operatively interconnecting at least one of the spider wheels with the gear means, a hydraulic piston mounted for axial adjustment in the hub hydraulic compartment, and high pressure conduit means operatively communicating each end of the hub hydraulic compartment with the hydraulic actuator.

12. Propulsion mechanism as claimed in claim 1 wherein a pair of disk-like plates are mounted coaxially of the axis of wheel rotation, the blades extend transversely between said plates, and at least one of the plates has an aperture therein openly communicating the space between the plates with the ambient atmosphere beyond the plates to generate an air flow inwardly through such aperture and radially outwardly between the blades upon rotation of the disks and blades in the manner of a squirrel cage blower.

13. The method of water craft propulsion which comprises creating a smooth wake aft of a planing element of such craft when the craft is traveling forward at and above a selected speed, severing a succession of chiplike segments from the surface of the wake, propelling each such segment by inertia upwardly and then rearwardly along a concavely curved face, and discharging each such segment rearwardly above the wake at a speed exceeding the lineal speed of the concavely curved face, the segments being severed and discharged in such rapid succession as to comprise a pulse jet stream propelling the craft forward.

14. A propulsion method for water craft comprising the steps of tangentially cutting successive chips from the water surface at a tangential speed which exceeds the forward speed of the craft thereby to cause movement of the chips in response to inertial forces imparted thereto, and directing said movement of the chips along a predetermined path for discharge of the same as a pulsed jet stream through the air rearwardly of the craft at a velocity which exceeds said tangential speed whereby said stream produces a reaction thrust to propel the craft over the water at said forward speed.

15. The propulsion method as in the preceding claim 14 in which the chips are directed and moved along a circular path upwardly of the water surface and rearwardly of the craft.

[6. The propulsion method as in the preceding claim 14 in which the thrust T of the jet stream is expressed by the equation:

T=2e wd(Vp- V) V where:

e is the mass density of the water w is the width of cut or chip width d is the average depth of cut or chip thickness Vp is the tangential cutting speed V is the velocity of the craft 2(Vp-V) is the velocity Ve of the chip l7. Tangential flow jet pump propulsion mechanism for a water craft comprising:

a. means for tangentially cutting successive chips from the water surface at a tangential speed which exceeds the forward speed of the craft thereby to cause movement of the chips in response to inertial forces imparted thereto; and

said directing means includes means for directing and moving the chips along a circular path upwardly of the water surface and rearwardly of the craft.

l9. Propulsion mechanism as in claim 17 in which the thrust T of the jet stream is expressed by the equation;

where:

e is the mass density of the water w is the width of cut or chip width d is the average depth of cut or chip thickness Vp is the tangential cutting speed V is the velocity of the craft 2( Vp-V) is the velocity Ve of the chip. t 

1. Pulse jet pump type propulsion mechanism for a water craft comprising, in combination with a hull, a planning surface on the hull for providing a smooth wake astern thereof with the craft moving ahead at and above a selected speed, a propulsion wheel journaled on the hull for rotation about an axis extending transversely of the hull above the zone of such wake, a plurality of concavo-convex curved blades mounted peripherally about said wheel, each blade having its concavely curved face of selected width and curvature for facing in the direction of forward rotation of the wheel, the wheel being mounted at a height on the hull to immerse only a selected tip portion of each blade in such wake at the nadir of blade orbit with the craft traveling forward at and above such selected speed, and power drive means for rotatively driving the wheel in its forward direction at a peripheral speed sufficiently greater than such selected hull speed that the tip of each blade severs such chip-like segment of water from the surface of such wake, and propels such segment by inertia radially inwardly around the concave face of the blade, the curvature of each blade at its radially inward edge continuing past a radial plane of the wheel tangent thereto, whereby each such segment is discharged rearwardly above such wake at a speed greater than blade orbital speed.
 2. Propulsion mechanism as claimed in claim 1 wherein the tip of each blade is so angularly positioned relative to a radial plane from the wheel axis through the blade tip that with the hull traveling forward at a speed to create such wake, and the wheel rotatively driven to sever and propel such chip-like segments from the wake, the blade tip enters the wake at a relative angle of attack to cut smoothly into the wake.
 3. Propulsion mechanism as claimed in claim 2 wherein the relative angle of attack of the blade is slightly positive.
 4. Propulsion mechanism as claimed in claim 1 wherein the tip of each blade is sharpened to a cutting edge.
 5. Propulsion mechanism as claimed in claim 1 wherein a wake-creating element of the hull bottom ahead of the wheel is adjustable for controlling the immersion depth of the wheel in the wake, and means for adjusting said wake creating element.
 6. Propulsion mechanism as claimed in claim 1 wherein each of the blades is angularly adjustable relative to a radial plane from the axis of wheel rotation to a selected portion of the blade.
 7. Propulsion mechanism as claimed in claim 6 wherein all of the blades are operatively interconnected for synchronous angular adjustment.
 8. Propulsion mechanism as claimed in claim 7 whereiN each of the blades is rotatively adjustable about an axis parallel to the axis of wheel rotation, and all of the axes of blade adjustment are spaced equally from the axis of wheel rotation.
 9. Propulsion mechanism as claimed in claim 8 wherein the blades are adjustable from a position wherein their concave sides face in the direction of forward rotation of the wheel, to a position wherein their concave sides face in the direction of reverse rotation of the wheel.
 10. Propulsion mechanism as claimed in claim 9 wherein a gear segment is secured to each blade co-axially of its axis of adjustment, gear means mounted co-axially of the wheel and in mesh with a gear segment connected to each blade, said gear means being rotatively adjustable about the axis of wheel rotation, and actuating means operatively mounted between the gear means and the wheel to control the rotative position of the gear means relative to the wheel, and thereby the adjusted angular position of the blades.
 11. Propulsion mechanism as claimed in claim 10 wherein the wheel comprises a hub having a cylindrical hydraulic compartment co-axially therein, a plurality of spider wheels mounted co-axially on the hub in symmetrical, axially spaced relation, a plurality of blades mounted in aligned rows between the spider wheels, the blades of each row being interconnected to each other and to at least one of the gear segments for rotative adjustment about a common axis parallel to the hub axis, the actuating means comprises a hydraulic actuator operatively interconnecting at least one of the spider wheels with the gear means, a hydraulic piston mounted for axial adjustment in the hub hydraulic compartment, and high pressure conduit means operatively communicating each end of the hub hydraulic compartment with the hydraulic actuator.
 12. Propulsion mechanism as claimed in claim 1 wherein a pair of disk-like plates are mounted co-axially of the axis of wheel rotation, the blades extend transversely between said plates, and at least one of the plates has an aperture therein openly communicating the space between the plates with the ambient atmosphere beyond the plates to generate an air flow inwardly through such aperture and radially outwardly between the blades upon rotation of the disks and blades in the manner of a squirrel cage blower.
 13. The method of water craft propulsion which comprises creating a smooth wake aft of a planing element of such craft when the craft is traveling forward at and above a selected speed, severing a succession of chip-like segments from the surface of the wake, propelling each such segment by inertia upwardly and then rearwardly along a concavely curved face, and discharging each such segment rearwardly above the wake at a speed exceeding the lineal speed of the concavely curved face, the segments being severed and discharged in such rapid succession as to comprise a pulse jet stream propelling the craft forward.
 14. A propulsion method for water craft comprising the steps of tangentially cutting successive chips from the water surface at a tangential speed which exceeds the forward speed of the craft thereby to cause movement of the chips in response to inertial forces imparted thereto, and directing said movement of the chips along a predetermined path for discharge of the same as a pulsed jet stream through the air rearwardly of the craft at a velocity which exceeds said tangential speed whereby said stream produces a reaction thrust to propel the craft over the water at said forward speed.
 15. The propulsion method as in the preceding claim 14 in which the chips are directed and moved along a circular path upwardly of the water surface and rearwardly of the craft.
 16. The propulsion method as in the preceding claim 14 in which the thrust T of the jet stream is expressed by the equation: T 2e wd (Vp - V) V where: e is the mass density of the water w is the width of cut or chip width d is the average depth of cut or chip thickness Vp is the tangential cutting speed V is the velocity of the craft 2(Vp-V) is the velocity Ve of the chip
 17. Tangential flow jet pump propulsion mechanism for a water craft comprising: a. means for tangentially cutting successive chips from the water surface at a tangential speed which exceeds the forward speed of the craft thereby to cause movement of the chips in response to inertial forces imparted thereto; and b. means for directing said movement of the chips along a predetermined path for discharge of the same in the form of a pulsed jet stream through the air rearwardly of the craft at a velocity which exceeds said tangential speed whereby said stream produces a reaction thrust to propel the craft over the water at said forward speed.
 18. Propulsion mechanism as in claim 17 wherein said directing means includes means for directing and moving the chips along a circular path upwardly of the water surface and rearwardly of the craft.
 19. Propulsion mechanism as in claim 17 in which the thrust T of the jet stream is expressed by the equation; T 2e wd (Vp - V) V where: e is the mass density of the water w is the width of cut or chip width d is the average depth of cut or chip thickness Vp is the tangential cutting speed V is the velocity of the craft 2(Vp-V) is the velocity Ve of the chip. 